Every time I try to sync my iPhone to the songs on my MacBook it constantly keeps re-syncing the same ones over and over. I have my songs compressed before they are synced so this ends up being a lengthy process.
The songs in question are all from one artist, the hundreds of other artists I have on there never re-sync.
iPhone 3GS 5.1.1 MacBook Pro 2009 OSX 10.6.8 iTunes 10.6.3